Pictures speak louder than words, so below is a quick tutorial on how to get an off-the-shelf TomyTec Japanese Shop Building lit with LED lighting. In total, this building received 6 LEDs; lantern, side-door, top floor (x2), bottom floor (x2).
Interior Lighting + Side Door
The trickiest part of this installation was the lantern that hangs out the front. I actually sliced it in half and bored out the middle to fit an LED inside. I also trimmed down the LED with a file to get it to fit a little more easily. This was done with my pocket-knife and I stopped when I felt it grinding metal. :)
Note that I borrowed ideas from this blog and I strongly recommend you check out the work the author has done on their layout!
And finally, everything is wired up. You can see the huge hole I accidently drilled in the side of the shop... luckily the lantern covers it over pretty well.